A related invention is described in U.S. patent application Ser. No. 07/793,912, to Eyl for "Method and Apparatus for Handling Signals in a Logging Device" filed the same day as this application, and assigned to the same assignee.
The invention relates to investigating earth formations traversed by a borehole, and more particularly to a logging apparatus having a wall engaging pad for determining the petrophysical characteristics of the formations.
Numerous logging devices are known that include one or more pads suitable for being pressed against the wall of a borehole by means of a spring for the purpose of generating measurement signals representative of the physical parameters of the geological formations through which the borehole passes. One example of a device including a pad pressed against the wall of a borehole is described in U.S. Pat. No. 4,692,908 (Ekstrom et al.). The pad carries an array of electrodes and an array of acoustic transducers.
In order to satisfy present development of logging devices, it is necessary to provide pads of increasing complexity. It is therefore advantageous to be able to provide such pads in a form which is as compact as possible and which enable modifications to be performed either to satisfy differing local requirements, or else to enable future improvements or additions to be installed.